지층 및 지하수 방사성 폐기물

포항공과대학교
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페이스북 트위터 카카오톡 네이버밴드 링크복사

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공학 >정밀ㆍ에너지 >원자력공학
강의학기

2013년 1학기

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4,008

This course provides the graduate students for an overview of fundamental radiochemistry and hydro geochemistry associated with environmental nuclear wastes on soils and groundwater.

수강안내 및 수강신청
※ 수강확인증 발급을 위해서는 수강신청이 필요합니다

Introduction of the courses

차시별 강의

1.	Introduction of the courses	introduction of radioactive wastes and contaminants were taught.
2.	Fundamentals of radiochemistry	fundamentals of radiochemistry, radioactivity, and radiation were taught.
	Fundamentals of radiochemistry (cont.)	fundamentals of radiochemistry were continuously taught.
3.	Fundamentals of radiochemistry and wastes	fundamentals of radiochemistry and wastes were taught.
	Fundamentals of radiochemistry and wastes	radioactive wastes and contamination were taught.
	Fundamentals of radiochemistry	radioactive wastes and contamination were taught.
4.	Actinide chemistry	actinide chemistry and radiation measurements were taught.
	Aqueous chemistry	aqueous chemistry background was taught.
5.	Glass corrosion	The complexity of glass corrosion requires deep knowledge of diffusion, interfacial heterogeneous reaction, and hydrothermal precipitation of minerals in highly multicomponent media. Basic concepts and relations are introduced.
6.	Chemical durability	Only short-term resistance of glass against corrosion (durability) can be measured in the laboratory using a series of standardized tests. Long-term (over 105 to 106 years) durability can only be assessed.
	crystallization and chemical durability	Waste glass crystallization must not degrade glass durability. Therefore, canister-centerline cooled glasses are tested pro durability. Out of many crystalline forms, nepheline appears the most insidious.
7.	Waste glass processing	Waste glass technology differs from commercial glass technology in many aspects: the waste is given, only additive raw materials can be selected; feed may be charged in the form of slurry; fining is not essential; etc.
8.	Melter feed makeup	Mineral form of additives and particle size influence cold cap stability and the rate of melting. Drainage of fluxes can destabilize the cold cap, leading to cold cap freezing. Evolved gases produce foam and cavities under the cold cap.
	Melting reactions	Melting reactions release copious gasses and produce intermediate crystalline forms. Eutectic melts of molten salts attack refractory particles. Glass-forming melt tends to trap gases, creating foam. Melter feed reacts while moving down across the cold cap as the heat is conducted upward.
9.	Batch calculation	Glass component can be present in more than one batch material. Matrix calculus is used for designing complex batches. Back calculation is essential. Feed simulants must be carefully designed.
	Thermal analysis	Thermogravimetric analysis (TGA) and differential scanning calorimetry (DCS) measure the kinetics of batch reaction. Batch reactions are multiple and overlapping. Evolved glass analysis (EGA) allows gas-evolving reactions to be identified.
10.	X-ray diffraction and microscopy	Optical and electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and X-ray diffraction (XRD) are used for the identification of crystalline phases in glasses and in glass batches (melter feeds) during their conversion to molten glass.
	Segregation of molten salts	As nitrates and carbonates decompose, areas occupied by molten salts shrink leaving behind sulfates, chromates, pertechnetates, chlorides). These sparsely-soluble components accumulate in droplets and are transported to the melt surface.
11.	Silica (quartz) dissolution	Quartz, the major feed component, initially reacts with molten salts and then dissolves in melt via diffusion. Diffusion is affected by the formation, growth and motion of gas bubbles. Large grains tend to cluster.
	Silica (quartz) dissolution	Quartz, the major feed component, initially reacts with molten salts and then dissolves in melt via diffusion. Diffusion is affected by the formation, growth and motion of gas bubbles. Large grains tend to cluster.
12.	Volatilization	Volatile species evaporate from the cold cap and escape from the melt to bubbles and the atmosphere. Their Henry’s coefficients are large. The rate of volatilization is controlled by diffusion both in gas and melt. Buoyancy-driven and surface-tension-gradient-driven convection in melt enhance volatilization.
	Redox equilibria	Multivalent species are common in waste glasses. Redox reactions generate oxygen bubbles and metal droplets. Redox ratio increases as temperature increases and optical basicity decreases.
13.	Foaming	Batch gases generate primary foam, redox reaction lead to secondary foam. Foam accumulated under the cold cap slows the melting process by reducing heat transfer. Foam collapses through met drainage and breaking the liquid films separating foam cells.
	Settling of solids	Solids of crystalline phases (spinel) can settle on the melter bottom and can block the melt discharge. Crystals settle while growing and dissolving in the melt and form a dense sludge that can be electrically conductive.
14.	Glass melters	Joule-heated melters use resistance heating via inconel electrodes. Induction-heated melters generate heat electromagnetically either in the crucible wall or within the melt.
	Modeling	The basic balance laws with constitutive relations form a system of coupled field equations to be solved for problems defined by the boundary conditions. Mathematical models of melters display the electric, temperature, and velocity fields in molten glass and furnace atmosphere. Models can also include redox equilibria, bubble behavior, and solid particle growth, dissolution, and settling.
15.	Refractory end electrode corrosion	Molten glass and salts corrode refractory walls of melters by dissolving refractory materials via diffusion under free or forced convection. Intergranular diffusion is also common. Surface tension gradients drive melt-line corrosion and bubble/droplet drilling.
	Revision	Topics selected by students are further elucidated.